require 'spec_helper'

describe Mongo::Collection do

  before do
    authorized_collection.drop
  end

  let(:collection_invalid_write_concern) do
    authorized_collection.client.with(write: INVALID_WRITE_CONCERN)[authorized_collection.name]
  end

  let(:collection_with_validator) do
    authorized_client[:validating]
  end

  let(:client) do
    authorized_client
  end

  describe '#==' do

    let(:database) do
      Mongo::Database.new(authorized_client, :test)
    end

    let(:collection) do
      described_class.new(database, :users)
    end

    context 'when the names are the same' do

      context 'when the databases are the same' do

        let(:other) do
          described_class.new(database, :users)
        end

        it 'returns true' do
          expect(collection).to eq(other)
        end
      end

      context 'when the databases are not the same' do

        let(:other_db) do
          Mongo::Database.new(authorized_client, :testing)
        end

        let(:other) do
          described_class.new(other_db, :users)
        end

        it 'returns false' do
          expect(collection).to_not eq(other)
        end
      end

      context 'when the options are the same' do

        let(:other) do
          described_class.new(database, :users)
        end

        it 'returns true' do
          expect(collection).to eq(other)
        end
      end

      context 'when the options are not the same' do

        let(:other) do
          described_class.new(database, :users, :capped => true)
        end

        it 'returns false' do
          expect(collection).to_not eq(other)
        end
      end
    end

    context 'when the names are not the same' do

      let(:other) do
        described_class.new(database, :sounds)
      end

      it 'returns false' do
        expect(collection).to_not eq(other)
      end
    end

    context 'when the object is not a collection' do

      it 'returns false' do
        expect(collection).to_not eq('test')
      end
    end
  end

  describe '#with' do

    let(:client) do
      new_local_client(SpecConfig.instance.addresses, SpecConfig.instance.test_options)
    end

    let(:database) do
      Mongo::Database.new(client, :test)
    end

    let(:collection) do
      database.collection(:users)
    end

    let(:new_collection) do
      collection.with(new_options)
    end

    context 'when new read options are provided' do

      let(:new_options) do
        { read: { mode: :secondary } }
      end

      it 'returns a new collection' do
        expect(new_collection).not_to be(collection)
      end

      it 'sets the new read options on the new collection' do
        expect(new_collection.read_preference).to eq(new_options[:read])
      end

      context 'when the client has a server selection timeout setting' do

        let(:client) do
          new_local_client(SpecConfig.instance.addresses, SpecConfig.instance.test_options.merge(server_selection_timeout: 2))
        end

        it 'passes the the server_selection_timeout to the cluster' do
          expect(client.cluster.options[:server_selection_timeout]).to eq(client.options[:server_selection_timeout])
        end
      end

      context 'when the client has a read preference set' do

        let(:client) do
          new_local_client(SpecConfig.instance.addresses, SpecConfig.instance.test_options.merge(read: { mode: :primary_preferred }))
        end

        it 'sets the new read options on the new collection' do
          expect(new_collection.read_preference).to eq(new_options[:read])
          expect(new_collection.read_preference).not_to eq(client.read_preference)
        end
      end

      context 'when the client has a read preference and server selection timeout set' do

        let(:client) do
          new_local_client(SpecConfig.instance.addresses, SpecConfig.instance.test_options.merge(read: { mode: :primary_preferred }, server_selection_timeout: 2))
        end

        it 'sets the new read options on the new collection' do
          expect(new_collection.read_preference).to eq(new_options[:read])
        end

        it 'passes the server_selection_timeout setting to the cluster' do
          expect(client.cluster.options[:server_selection_timeout]).to eq(client.options[:server_selection_timeout])
        end
      end
    end

    context 'when new write options are provided' do

      let(:new_options) do
        { write: { w: 5 } }
      end

      it 'returns a new collection' do
        expect(new_collection).not_to be(collection)
      end

      it 'sets the new write options on the new collection' do
        expect(new_collection.write_concern.options).to eq(Mongo::WriteConcern.get(new_options[:write]).options)
      end

      context 'when the client has a write concern set' do

        let(:client) do
          new_local_client(SpecConfig.instance.addresses, SpecConfig.instance.test_options.merge(write: INVALID_WRITE_CONCERN))
        end

        it 'sets the new write options on the new collection' do
          expect(new_collection.write_concern.options).to eq(Mongo::WriteConcern.get(new_options[:write]).options)
        end
      end
    end

    context 'when new read and write options are provided' do

      let(:new_options) do
        {
          read: { mode: :secondary },
          write: { w: 4}
        }
      end

      it 'returns a new collection' do
        expect(new_collection).not_to be(collection)
      end

      it 'sets the new read options on the new collection' do
        expect(new_collection.read_preference).to eq(new_options[:read])
      end

      it 'sets the new write options on the new collection' do
        expect(new_collection.write_concern.options).to eq(Mongo::WriteConcern.get(new_options[:write]).options)
      end

      context 'when the client has a server selection timeout setting' do

        let(:client) do
          new_local_client(SpecConfig.instance.addresses, SpecConfig.instance.test_options.merge(server_selection_timeout: 2))
        end

        it 'passes the server_selection_timeout setting to the cluster' do
          expect(client.cluster.options[:server_selection_timeout]).to eq(client.options[:server_selection_timeout])
        end
      end

      context 'when the client has a read preference set' do

        let(:client) do
          new_local_client(SpecConfig.instance.addresses, SpecConfig.instance.test_options.merge(read: { mode: :primary_preferred }))
        end

        it 'sets the new read options on the new collection' do
          expect(new_collection.read_preference).to eq(new_options[:read])
          expect(new_collection.read_preference).not_to be(client.read_preference)
        end
      end
    end

    context 'when neither read nor write options are provided' do

      let(:new_options) do
        { some_option: 'invalid' }
      end

      it 'raises an error' do
        expect {
          new_collection
        }.to raise_exception(Mongo::Error::UnchangeableCollectionOption)
      end
    end
  end

  describe '#read_preference' do

    let(:collection) do
      described_class.new(authorized_client.database, :users, options)
    end

    let(:options) { {} }

    context 'when a read preference is set in the options' do

      let(:options) do
        { read: { mode: :secondary } }
      end

      it 'returns the read preference' do
        expect(collection.read_preference).to eq(options[:read])
      end
    end

    context 'when a read preference is not set in the options' do

      context 'when the database has a read preference set' do

        let(:client) do
          authorized_client.with(read: { mode: :secondary_preferred })
        end

        let(:collection) do
          described_class.new(client.database, :users, options)
        end

        it 'returns the database read preference' do
          expect(collection.read_preference).to eq(BSON::Document.new({ mode: :secondary_preferred }))
        end
      end

      context 'when the database does not have a read preference' do

        it 'returns nil' do
          expect(collection.read_preference).to be_nil
        end
      end
    end
  end

  describe '#server_selector' do

    let(:collection) do
      described_class.new(authorized_client.database, :users, options)
    end

    let(:options) { {} }

    context 'when a read preference is set in the options' do

      let(:options) do
        { read: { mode: :secondary } }
      end

      it 'returns the server selector for that read preference' do
        expect(collection.server_selector).to be_a(Mongo::ServerSelector::Secondary)
      end
    end

    context 'when a read preference is not set in the options' do

      context 'when the database has a read preference set' do

        let(:client) do
          authorized_client.with(read: { mode: :secondary_preferred })
        end

        let(:collection) do
          described_class.new(client.database, :users, options)
        end

        it 'returns the server selector for that read preference' do
          expect(collection.server_selector).to be_a(Mongo::ServerSelector::SecondaryPreferred)
        end
      end

      context 'when the database does not have a read preference' do

        it 'returns a primary server selector' do
          expect(collection.server_selector).to be_a(Mongo::ServerSelector::Primary)
        end
      end
    end
  end

  describe '#capped?' do

    let(:database) do
      authorized_client.database
    end

    context 'when the collection is capped' do

      let(:collection) do
        described_class.new(database, :specs, :capped => true, :size => 1024)
      end

      before do
        authorized_client[:specs].drop
        collection.create
      end

      it 'returns true' do
        expect(collection).to be_capped
      end
    end

    context 'when the collection is not capped' do

      let(:collection) do
        described_class.new(database, :specs)
      end

      before do
        authorized_client[:specs].drop
        collection.create
      end

      it 'returns false' do
        expect(collection).to_not be_capped
      end
    end
  end

  describe '#create' do
    before do
      authorized_client[:specs].drop
    end

    let(:database) do
      authorized_client.database
    end

    context 'when the collection has no options' do

      let(:collection) do
        described_class.new(database, :specs)
      end

      let!(:response) do
        collection.create
      end

      it 'executes the command' do
        expect(response).to be_successful
      end

      it 'creates the collection in the database' do
        expect(database.collection_names).to include('specs')
      end
    end

    context 'when the collection has options' do

      context 'when the collection is capped' do

        shared_examples 'a capped collection command' do

          let!(:response) do
            collection.create
          end

          let(:options) do
            { :capped => true, :size => 1024 }
          end

          it 'executes the command' do
            expect(response).to be_successful
          end

          it 'sets the collection as capped' do
            expect(collection).to be_capped
          end

          it 'creates the collection in the database' do
            expect(database.collection_names).to include('specs')
          end
        end

        shared_examples 'a validated collection command' do

          let!(:response) do
            collection.create
          end

          let(:options) do
            { :validator => { fieldName: { '$gte' =>  1024 } },
              :validationLevel => 'strict' }
          end

          let(:collection_info) do
            database.list_collections.find { |i| i['name'] == 'specs' }
          end

          it 'executes the command' do
            expect(response).to be_successful
          end

          it 'sets the collection with validators' do
            expect(collection_info['options']['validator']).to eq({ 'fieldName' => { '$gte' => 1024 } })
          end

          it 'creates the collection in the database' do
            expect(database.collection_names).to include('specs')
          end
        end

        context 'when instantiating a collection directly' do

          let(:collection) do
            described_class.new(database, :specs, options)
          end

          it_behaves_like 'a capped collection command'

          context 'when validators can be set' do
            min_server_version '3.2'
            it_behaves_like 'a validated collection command'
          end
        end

        context 'when instantiating a collection through the database' do

          let(:collection) do
            authorized_client[:specs, options]
          end

          it_behaves_like 'a capped collection command'

          context 'when validators can be set' do
            min_server_version '3.2'
            it_behaves_like 'a validated collection command'
          end
        end
      end

      context 'when the collection has a write concern' do

        before do
          database[:specs].drop
        end

        let(:options) do
          {
            write: INVALID_WRITE_CONCERN
          }
        end

        let(:collection) do
          described_class.new(database, :specs, options)
        end

        context 'when the server supports write concern on the create command', if: replica_set? && collation_enabled? do

          it 'applies the write concern' do
            expect{
              collection.create
            }.to raise_exception(Mongo::Error::OperationFailure)
          end
        end

        context 'when the server does not support write concern on the create command', unless: collation_enabled? do

          it 'does not apply the write concern' do
            expect(collection.create).to be_successful
          end
        end
      end

      context 'when the collection has a collation' do

        shared_examples 'a collection command with a collation option' do

          let(:response) do
            collection.create
          end

          let(:options) do
            { :collation => { locale: 'fr' } }
          end

          let(:collection_info) do
            database.list_collections.find { |i| i['name'] == 'specs' }
          end

          before do
            collection.drop
          end

          context 'when the server supports collations', if: collation_enabled? do

            it 'executes the command' do
              expect(response).to be_successful
            end

            it 'sets the collection with a collation' do
              response
              expect(collection_info['options']['collation']['locale']).to eq('fr')
            end

            it 'creates the collection in the database' do
              response
              expect(database.collection_names).to include('specs')
            end
          end

          context 'when the server does not support collations', unless: collation_enabled? do

            it 'raises an error' do
              expect {
                response
              }.to raise_exception(Mongo::Error::UnsupportedCollation)
            end

            context 'when a String key is used' do

              let(:options) do
                { 'collation' => { locale: 'fr' } }
              end

              it 'raises an exception' do
                expect {
                  response
                }.to raise_exception(Mongo::Error::UnsupportedCollation)
              end
            end
          end
        end

        context 'when instantiating a collection directly' do

          let(:collection) do
            described_class.new(database, :specs, options)
          end

          it_behaves_like 'a collection command with a collation option'
        end

        context 'when instantiating a collection through the database' do

          let(:collection) do
            authorized_client[:specs, options]
          end

          it_behaves_like 'a collection command with a collation option'
        end
      end

      context 'when a session is provided' do

        let(:collection) do
          authorized_client[:specs]
        end

        let(:operation) do
          collection.create(session: session)
        end

        let(:session) do
          authorized_client.start_session
        end

        let(:client) do
          authorized_client
        end

        let(:failed_operation) do
          authorized_client[:specs, invalid: true].create(session: session)
        end

        before do
          collection.drop
        end

        it_behaves_like 'an operation using a session'
        it_behaves_like 'a failed operation using a session'
      end
    end
  end

  describe '#drop' do

    let(:database) do
      authorized_client.database
    end

    let(:collection) do
      described_class.new(database, :specs)
    end

    context 'when the collection exists' do

      before do
        authorized_client[:specs].drop
        collection.create
        # wait for the collection to be created
        sleep 0.4
      end

      context 'when a session is provided' do

        let(:operation) do
          collection.drop(session: session)
        end

        let(:failed_operation) do
          collection.with(write: INVALID_WRITE_CONCERN).drop(session: session)
        end

        let(:session) do
          authorized_client.start_session
        end

        let(:client) do
          authorized_client
        end

        it_behaves_like 'an operation using a session'

        # Due to how rspec interprets nested `if: condition` guards, we can't use one to skip this
        # test in the case that the server will override the write concern (preventing the expected
        # failure), so we're forced to use a traditional conditional to avoid defining the test.
        it_behaves_like 'a failed operation using a session' if can_set_write_concern?
      end

      context 'when the collection does not have a write concern set' do

        let!(:response) do
          collection.drop
        end

        it 'executes the command' do
          expect(response).to be_successful
        end

        it 'drops the collection from the database' do
          expect(database.collection_names).to_not include('specs')
        end

        context 'when the collection does not exist', if: can_set_write_concern? do

          it 'does not raise an error' do
            expect(database['non-existent-coll'].drop).to be(false)
          end
        end
      end

      context 'when the collection has a write concern' do

        let(:write_options) do
          {
            write: INVALID_WRITE_CONCERN
          }
        end

        let(:collection_with_write_options) do
          collection.with(write_options)
        end

        context 'when the server supports write concern on the drop command', if: collation_enabled? && can_set_write_concern? do

          it 'applies the write concern' do
            expect{
              collection_with_write_options.drop
            }.to raise_exception(Mongo::Error::OperationFailure)
          end
        end

        context 'when the server does not support write concern on the drop command', unless: collation_enabled? do

          it 'does not apply the write concern' do
            expect(collection_with_write_options.drop).to be_successful
          end
        end
      end
    end

    context 'when the collection does not exist', if: can_set_write_concern? do
      before do
        begin
          collection.drop
        rescue Mongo::Error::OperationFailure
        end
      end

      it 'returns false' do
        expect(collection.drop).to be(false)
      end
    end
  end

  describe '#find' do

    describe 'updating cluster time' do

      let(:operation) do
        client[TEST_COLL].find.first
      end

      let(:operation_with_session) do
        client[TEST_COLL].find({}, session: session).first
      end

      let(:second_operation) do
        client[TEST_COLL].find({}, session: session).first
      end

      it_behaves_like 'an operation updating cluster time'
    end

    context 'when provided a filter' do

      let(:view) do
        authorized_collection.find(name: 1)
      end

      it 'returns a authorized_collection view for the filter' do
        expect(view.filter).to eq('name' => 1)
      end
    end

    context 'when provided no filter' do

      let(:view) do
        authorized_collection.find
      end

      it 'returns a authorized_collection view with an empty filter' do
        expect(view.filter).to be_empty
      end
    end

    context 'when providing a bad filter' do

      let(:view) do
        authorized_collection.find('$or' => [])
      end

      it 'raises an exception when iterating' do
        expect {
          view.to_a
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when iterating the authorized_collection view' do

      before do
        authorized_collection.insert_many([{ field: 'test1' }, { field: 'test2' }])
      end

      let(:view) do
        authorized_collection.find
      end

      it 'iterates over the documents' do
        view.each do |document|
          expect(document).to_not be_nil
        end
      end
    end

    context 'when the user is not authorized', if: auth_enabled? do

      let(:view) do
        unauthorized_collection.find
      end

      it 'iterates over the documents' do
        expect {
          view.each{ |document| document }
        }.to raise_error(Mongo::Error::OperationFailure)
      end
    end

    context 'when documents contain potential error message fields' do

      [ Mongo::Error::ERRMSG, Mongo::Error::ERROR, Mongo::Operation::Result::OK ].each do |field|

        context "when the document contains a '#{field}' field" do

          let(:value) do
            'testing'
          end

          let(:view) do
            authorized_collection.find
          end

          before do
            authorized_collection.insert_one({ field => value })
          end

          it 'iterates over the documents' do
            view.each do |document|
              expect(document[field]).to eq(value)
            end
          end
        end
      end
    end

    context 'when provided options' do

      context 'when a session is provided' do

        let(:operation) do
          authorized_collection.find({}, session: session).to_a
        end

        let(:session) do
          authorized_client.start_session
        end

        let(:failed_operation) do
          client[authorized_collection.name].find({ '$._id' => 1 }, session: session).to_a
        end

        let(:client) do
          authorized_client
        end

        it_behaves_like 'an operation using a session'
        it_behaves_like 'a failed operation using a session'
      end

      context 'session id' do
        min_server_version '3.6'
        require_topology :replica_set, :sharded

        let(:options) do
          { session: session }
        end

        let(:client) do
          subscribed_client
        end

        let(:session) do
          client.start_session
        end

        let(:view) do
          Mongo::Collection::View.new(client[TEST_COLL], selector, view_options)
        end

        let(:command) do
          client[TEST_COLL].find({}, session: session).explain
          EventSubscriber.started_events.find { |c| c.command_name == 'explain' }.command
        end

        it 'sends the session id' do
          expect(command['lsid']).to eq(session.session_id)
        end
      end

      context 'when a session supporting causal consistency is used' do

        let(:operation) do
          collection.find({}, session: session).to_a
        end

        let(:command) do
          operation
          EventSubscriber.started_events.find { |cmd| cmd.command_name == 'find' }.command
        end

        it_behaves_like 'an operation supporting causally consistent reads'
      end

      let(:view) do
        authorized_collection.find({}, options)
      end

      context 'when provided :allow_partial_results' do

        let(:options) do
          { allow_partial_results: true }
        end

        it 'returns a view with :allow_partial_results set' do
          expect(view.options[:allow_partial_results]).to be(options[:allow_partial_results])
        end
      end

      context 'when provided :batch_size' do

        let(:options) do
          { batch_size: 100 }
        end

        it 'returns a view with :batch_size set' do
          expect(view.options[:batch_size]).to eq(options[:batch_size])
        end
      end

      context 'when provided :comment' do

        let(:options) do
          { comment: 'slow query' }
        end

        it 'returns a view with :comment set' do
          expect(view.modifiers[:$comment]).to eq(options[:comment])
        end
      end

      context 'when provided :cursor_type' do

        let(:options) do
          { cursor_type: :tailable }
        end

        it 'returns a view with :cursor_type set' do
          expect(view.options[:cursor_type]).to eq(options[:cursor_type])
        end
      end

      context 'when provided :max_time_ms' do

        let(:options) do
          { max_time_ms: 500 }
        end

        it 'returns a view with :max_time_ms set' do
          expect(view.modifiers[:$maxTimeMS]).to eq(options[:max_time_ms])
        end
      end

      context 'when provided :modifiers' do

        let(:options) do
          { modifiers: { '$orderby' => Mongo::Index::ASCENDING } }
        end

        it 'returns a view with modifiers set' do
          expect(view.modifiers).to eq(options[:modifiers])
        end

        it 'dups the modifiers hash' do
          expect(view.modifiers).not_to be(options[:modifiers])
        end
      end

      context 'when provided :no_cursor_timeout' do

        let(:options) do
          { no_cursor_timeout: true }
        end

        it 'returns a view with :no_cursor_timeout set' do
          expect(view.options[:no_cursor_timeout]).to eq(options[:no_cursor_timeout])
        end
      end

      context 'when provided :oplog_replay' do

        let(:options) do
          { oplog_replay: false }
        end

        it 'returns a view with :oplog_replay set' do
          expect(view.options[:oplog_replay]).to eq(options[:oplog_replay])
        end
      end

      context 'when provided :projection' do

        let(:options) do
          { projection:  { 'x' => 1 } }
        end

        it 'returns a view with :projection set' do
          expect(view.options[:projection]).to eq(options[:projection])
        end
      end

      context 'when provided :skip' do

        let(:options) do
          { skip:  5 }
        end

        it 'returns a view with :skip set' do
          expect(view.options[:skip]).to eq(options[:skip])
        end
      end

      context 'when provided :sort' do

        let(:options) do
          { sort:  { 'x' => Mongo::Index::ASCENDING } }
        end

        it 'returns a view with :sort set' do
          expect(view.modifiers[:$orderby]).to eq(options[:sort])
        end
      end

      context 'when provided :collation' do

        let(:options) do
          { collation: { 'locale' => 'en_US' } }
        end

        it 'returns a view with :collation set' do
          expect(view.options[:collation]).to eq(options[:collation])
        end
      end
    end
  end

  describe '#insert_many' do

    let(:result) do
      authorized_collection.insert_many([{ name: 'test1' }, { name: 'test2' }])
    end

    it 'inserts the documents into the collection' do
      expect(result.inserted_count).to eq(2)
    end

    it 'contains the ids in the result' do
      expect(result.inserted_ids.size).to eq(2)
    end

    context 'when a session is provided' do

      let(:session) do
        authorized_client.start_session
      end

      let(:operation) do
        authorized_collection.insert_many([{ name: 'test1' }, { name: 'test2' }], session: session)
      end

      let(:failed_operation) do
        authorized_collection.insert_many([{ _id: 'test1' }, { _id: 'test1' }], session: session)
      end

      let(:client) do
        authorized_client
      end

      it_behaves_like 'an operation using a session'
      it_behaves_like 'a failed operation using a session'
    end

    context 'when unacknowledged writes is used with an explicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        authorized_collection.with(write: { w: 0 })
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.insert_many([{ name: 'test1' }, { name: 'test2' }], session: session)
      end

      it_behaves_like 'an explicit session with an unacknowledged write'
    end

    context 'when unacknowledged writes is used with an implicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        subscribed_client.with(write: { w: 0 })[TEST_COLL]
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.insert_many([{ name: 'test1' }, { name: 'test2' }])
      end

      it_behaves_like 'an implicit session with an unacknowledged write'
    end

    context 'when a document contains invalid keys' do

      let(:docs) do
        [ { 'first.name' => 'test1' }, { name: 'test2' } ]
      end

      it 'raises a BSON::String::IllegalKey exception' do
        expect {
          authorized_collection.insert_many(docs)
        }.to raise_exception(BSON::String::IllegalKey)
      end
    end

    context 'when the client has a custom id generator' do

      let(:generator) do
        Class.new do
          def generate
            1
          end
        end.new
      end

      let(:custom_client) do
        authorized_client.with(id_generator: generator)
      end

      let(:custom_collection) do
        custom_client['custom_id_generator_test_collection']
      end

      before do
        custom_collection.delete_many
        custom_collection.insert_many([{ name: 'testing' }])
        expect(custom_collection.count).to eq(1)
      end

      after do
        custom_client.close
      end

      it 'inserts with the custom id' do
        expect(custom_collection.count).to eq(1)
        expect(custom_collection.find.first[:_id]).to eq(1)
      end
    end

    context 'when the inserts fail' do

      let(:result) do
        authorized_collection.insert_many([{ _id: 1 }, { _id: 1 }])
      end

      it 'raises an BulkWriteError' do
        expect {
          result
        }.to raise_exception(Mongo::Error::BulkWriteError)
      end
    end

    context "when the documents exceed the max bson size" do

      let(:documents) do
        [{ '_id' => 1, 'name' => '1'*17000000 }]
      end

      it 'raises a MaxBSONSize error' do
        expect {
          authorized_collection.insert_many(documents)
        }.to raise_error(Mongo::Error::MaxBSONSize)
      end
    end

    context 'when the documents are sent with OP_MSG' do
      min_server_version '3.6'

      let(:client) do
        subscribed_client
      end

      let(:documents) do
        [{ '_id' => 1, 'name' => '1'*16777191 }, { '_id' => 'y' }]
      end

      before do
        client[TEST_COLL].insert_many(documents)
      end

      after do
        client.close
      end

      let(:insert_events) do
        EventSubscriber.started_events.select { |e| e.command_name == 'insert' }
      end

      it 'sends the documents in one OP_MSG' do
        expect(insert_events.size).to eq(1)
        expect(insert_events[0].command['documents']).to eq(documents)
      end
    end

    context 'when collection has a validator' do
      min_server_version '3.2'

      around(:each) do |spec|
        authorized_client[:validating].drop
        authorized_client[:validating,
                          :validator => { :a => { '$exists' => true } }].tap do |c|
          c.create
        end
        spec.run
        collection_with_validator.drop
      end

      context 'when the document is valid' do

        let(:result) do
          collection_with_validator.insert_many([{ a: 1 }, { a: 2 }])
        end

        it 'inserts successfully' do
          expect(result.inserted_count).to eq(2)
        end
      end

      context 'when the document is invalid' do

        context 'when bypass_document_validation is not set' do

          let(:result2) do
            collection_with_validator.insert_many([{ x: 1 }, { x: 2 }])
          end

          it 'raises a BulkWriteError' do
            expect {
              result2
            }.to raise_exception(Mongo::Error::BulkWriteError)
          end
        end

        context 'when bypass_document_validation is true' do

          let(:result3) do
            collection_with_validator.insert_many(
              [{ x: 1 }, { x: 2 }], :bypass_document_validation => true)
          end

          it 'inserts successfully' do
            expect(result3.inserted_count).to eq(2)
          end
        end
      end
    end

    context 'when unacknowledged writes is used' do

      let(:collection_with_unacknowledged_write_concern) do
        authorized_collection.with(write: { w: 0 })
      end

      let(:result) do
        collection_with_unacknowledged_write_concern.insert_many([{ _id: 1 }, { _id: 1 }])
      end

      it 'does not raise an exception' do
        expect(result.inserted_count).to be(0)
      end
    end
  end

  describe '#insert_one' do

    describe 'updating cluster time' do

      let(:operation) do
        client[TEST_COLL].insert_one({ name: 'testing' })
      end

      let(:operation_with_session) do
        client[TEST_COLL].insert_one({ name: 'testing' }, session: session)
      end

      let(:second_operation) do
        client[TEST_COLL].insert_one({ name: 'testing' }, session: session)
      end

      it_behaves_like 'an operation updating cluster time'
    end

    let(:result) do
      authorized_collection.insert_one({ name: 'testing' })
    end

    it 'inserts the document into the collection'do
      expect(result.written_count).to eq(1)
    end

    it 'contains the id in the result' do
      expect(result.inserted_id).to_not be_nil
    end

    context 'when a session is provided' do

      let(:session) do
        authorized_client.start_session
      end

      let(:operation) do
        authorized_collection.insert_one({ name: 'testing' }, session: session)
      end

      let(:failed_operation) do
        authorized_collection.insert_one({ _id: 'testing' })
        authorized_collection.insert_one({ _id: 'testing' }, session: session)
      end

      let(:client) do
        authorized_client
      end

      it_behaves_like 'an operation using a session'
      it_behaves_like 'a failed operation using a session'
    end

    context 'when unacknowledged writes is used with an explicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        authorized_collection.with(write: { w: 0 })
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.insert_one({ name: 'testing' }, session: session)
      end

      it_behaves_like 'an explicit session with an unacknowledged write'
    end

    context 'when unacknowledged writes is used with an implicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        subscribed_client.with(write: { w: 0 })[TEST_COLL]
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.insert_one({ name: 'testing' })
      end

      it_behaves_like 'an implicit session with an unacknowledged write'
    end

    context 'when the document contains invalid keys' do

      let(:doc) do
        { 'testing.test' => 'value' }
      end

      it 'raises a BSON::String::IllegalKey exception' do
        expect {
          authorized_collection.insert_one(doc)
        }.to raise_exception(BSON::String::IllegalKey)
      end
    end

    context 'when the insert fails' do

      let(:result) do
        authorized_collection.insert_one(_id: 1)
        authorized_collection.insert_one(_id: 1)
      end

      it 'raises an OperationFailure' do
        expect {
          result
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when the client has a custom id generator' do

      let(:generator) do
        Class.new do
          def generate
            1
          end
        end.new
      end

      let(:custom_client) do
        authorized_client.with(id_generator: generator)
      end

      let(:custom_collection) do
        custom_client[TEST_COLL]
      end

      before do
        custom_collection.delete_many
        custom_collection.insert_one({ name: 'testing' })
      end

      after do
        custom_client.close
      end

      it 'inserts with the custom id' do
        expect(custom_collection.find.first[:_id]).to eq(1)
      end
    end

    context 'when collection has a validator' do
      min_server_version '3.2'

      around(:each) do |spec|
        authorized_client[:validating,
                          :validator => { :a => { '$exists' => true } }].tap do |c|
          c.create
        end
        spec.run
        collection_with_validator.drop
      end

      context 'when the document is valid' do

        let(:result) do
          collection_with_validator.insert_one({ a: 1 })
        end

        it 'inserts successfully' do
          expect(result.written_count).to eq(1)
        end
      end

      context 'when the document is invalid' do

        context 'when bypass_document_validation is not set' do

          let(:result2) do
            collection_with_validator.insert_one({ x: 1 })
          end

          it 'raises a OperationFailure' do
            expect {
              result2
            }.to raise_exception(Mongo::Error::OperationFailure)
          end
        end

        context 'when bypass_document_validation is true' do

          let(:result3) do
            collection_with_validator.insert_one(
              { x: 1 }, :bypass_document_validation => true)
          end

          it 'inserts successfully' do
            expect(result3.written_count).to eq(1)
          end
        end
      end
    end
  end

  describe '#inspect' do

    it 'includes the object id' do
      expect(authorized_collection.inspect).to include(authorized_collection.object_id.to_s)
    end

    it 'includes the namespace' do
      expect(authorized_collection.inspect).to include(authorized_collection.namespace)
    end
  end

  describe '#indexes' do

    let(:index_spec) do
      { name: 1 }
    end

    let(:batch_size) { nil }

    let(:index_names) do
      authorized_collection.indexes(batch_size: batch_size).collect { |i| i['name'] }
    end

    before do
      authorized_collection.indexes.create_one(index_spec, unique: true)
    end

    it 'returns a list of indexes' do
      expect(index_names).to include(*'name_1', '_id_')
    end

    context 'when a session is provided' do

      let(:session) do
        authorized_client.start_session
      end

      let(:operation) do
        authorized_collection.indexes(batch_size: batch_size, session: session).collect { |i| i['name'] }
      end

      let(:failed_operation) do
        authorized_collection.indexes(batch_size: -100, session: session).collect { |i| i['name'] }
      end

      let(:client) do
        authorized_client
      end

      it_behaves_like 'an operation using a session'
      it_behaves_like 'a failed operation using a session'
    end

    context 'when batch size is specified', unless: need_to_skip_on_sharded_auth_40? do

      let(:batch_size) { 1 }

      it 'returns a list of indexes' do
        expect(index_names).to include(*'name_1', '_id_')
      end
    end
  end

  describe '#aggregate' do

    describe 'updating cluster time' do

      let(:operation) do
        client[TEST_COLL].aggregate([]).first
      end

      let(:operation_with_session) do
        client[TEST_COLL].aggregate([], session: session).first
      end

      let(:second_operation) do
        client[TEST_COLL].aggregate([], session: session).first
      end

      it_behaves_like 'an operation updating cluster time'
    end

    context 'when a session supporting causal consistency is used' do

      let(:operation) do
        collection.aggregate([], session: session).first
      end

      let(:command) do
        operation
        EventSubscriber.started_events.find { |cmd| cmd.command_name == 'aggregate' }.command
      end

      it_behaves_like 'an operation supporting causally consistent reads'
    end

    it 'returns an Aggregation object' do
      expect(authorized_collection.aggregate([])).to be_a(Mongo::Collection::View::Aggregation)
    end

    context 'when options are provided' do

      let(:options) do
        { :allow_disk_use => true, :bypass_document_validation => true }
      end

      it 'sets the options on the Aggregation object' do
        expect(authorized_collection.aggregate([], options).options).to eq(BSON::Document.new(options))
      end

      context 'when the :comment option is provided' do

        let(:options) do
          { :comment => 'testing' }
        end

        it 'sets the options on the Aggregation object' do
          expect(authorized_collection.aggregate([], options).options).to eq(BSON::Document.new(options))
        end
      end

      context 'when a session is provided' do

        let(:session) do
          authorized_client.start_session
        end

        let(:operation) do
          authorized_collection.aggregate([], session: session).to_a
        end

        let(:failed_operation) do
          authorized_collection.aggregate([ { '$invalid' => 1 }], session: session).to_a
        end

        let(:client) do
          authorized_client
        end

        it_behaves_like 'an operation using a session'
        it_behaves_like 'a failed operation using a session'
      end

      context 'when a hint is provided' do

        let(:options) do
          { 'hint' => { 'y' => 1 } }
        end

        it 'sets the options on the Aggregation object' do
          expect(authorized_collection.aggregate([], options).options).to eq(options)
        end
      end

      context 'when collation is provided' do

        before do
          authorized_collection.insert_many([ { name: 'bang' }, { name: 'bang' }])
        end

        let(:pipeline) do
          [{ "$match" => { "name" => "BANG" } }]
        end

        let(:options) do
          { collation: { locale: 'en_US', strength: 2 } }
        end

        let(:result) do
          authorized_collection.aggregate(pipeline, options).collect { |doc| doc['name']}
        end

        context 'when the server selected supports collations', if: collation_enabled? do

          it 'applies the collation' do
            expect(result).to eq(['bang', 'bang'])
          end
        end

        context 'when the server selected does not support collations', unless: collation_enabled? do

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end

          context 'when a String key is used' do

            let(:options) do
              { 'collation' => { locale: 'en_US', strength: 2 } }
            end

            it 'raises an exception' do
              expect {
                result
              }.to raise_exception(Mongo::Error::UnsupportedCollation)
            end
          end
        end
      end
    end
  end

  describe '#count' do

    let(:documents) do
      (1..10).map{ |i| { field: "test#{i}" }}
    end

    before do
      authorized_collection.insert_many(documents)
    end

    it 'returns an integer count' do
      expect(authorized_collection.count).to eq(10)
    end

    context 'when options are provided' do

      it 'passes the options to the count' do
        expect(authorized_collection.count({}, limit: 5)).to eq(5)
      end

      context 'when a session is provided' do

        let(:session) do
          authorized_client.start_session
        end

        let(:operation) do
          authorized_collection.count({}, session: session)
        end

        let(:failed_operation) do
          authorized_collection.count({ '$._id' => 1 }, session: session)
        end

        let(:client) do
          authorized_client
        end

        it_behaves_like 'an operation using a session'
        it_behaves_like 'a failed operation using a session'
      end

      context 'when a session supporting causal consistency is used' do

        let(:operation) do
          collection.count({}, session: session)
        end

        let(:command) do
          operation
          EventSubscriber.started_events.find { |cmd| cmd.command_name == 'count' }.command
        end

        it_behaves_like 'an operation supporting causally consistent reads'
      end

      context 'when a collation is specified' do

        let(:selector) do
          { name: 'BANG' }
        end

        let(:result) do
          authorized_collection.count(selector, options)
        end

        before do
          authorized_collection.insert_one(name: 'bang')
        end

        let(:options) do
          { collation: { locale: 'en_US', strength: 2 } }
        end

        context 'when the server selected supports collations', if: collation_enabled? do

          it 'applies the collation to the count' do
            expect(result).to eq(1)
          end
        end

        context 'when the server selected does not support collations', unless: collation_enabled? do

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end

          context 'when a String key is used' do

            let(:options) do
              { 'collation' => { locale: 'en_US', strength: 2 } }
            end

            it 'raises an exception' do
              expect {
                result
              }.to raise_exception(Mongo::Error::UnsupportedCollation)
            end
          end
        end
      end
    end
  end

  describe '#distinct' do

    let(:documents) do
      (1..3).map{ |i| { field: "test#{i}" }}
    end

    before do
      authorized_collection.insert_many(documents)
    end

    it 'returns the distinct values' do
      expect(authorized_collection.distinct(:field).sort).to eq([ 'test1', 'test2', 'test3' ])
    end

    context 'when a selector is provided' do

      it 'returns the distinct values' do
        expect(authorized_collection.distinct(:field, field: 'test1')).to eq([ 'test1' ])
      end
    end

    context 'when options are provided' do

      it 'passes the options to the distinct command' do
        expect(authorized_collection.distinct(:field, {}, max_time_ms: 100).sort).to eq([ 'test1', 'test2', 'test3' ])
      end

      context 'when a session is provided' do

        let(:session) do
          authorized_client.start_session
        end

        let(:operation) do
          authorized_collection.distinct(:field, {}, session: session)
        end

        let(:failed_operation) do
          authorized_collection.distinct(:field, { '$._id' => 1 }, session: session)
        end

        let(:client) do
          authorized_client
        end

        it_behaves_like 'an operation using a session'
        it_behaves_like 'a failed operation using a session'
      end
    end

    context 'when a session supporting causal consistency is used' do

      let(:operation) do
        collection.distinct(:field, {}, session: session)
      end

      let(:command) do
        operation
        EventSubscriber.started_events.find { |cmd| cmd.command_name == 'distinct' }.command
      end

      it_behaves_like 'an operation supporting causally consistent reads'
    end

    context 'when a collation is specified' do

      let(:result) do
        authorized_collection.distinct(:name, {}, options)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
        authorized_collection.insert_one(name: 'BANG')
      end

      let(:options) do
        { collation: { locale: 'en_US', strength: 2 } }
      end

      context 'when the server selected supports collations', if: collation_enabled? do

        it 'applies the collation to the distinct' do
          expect(result).to eq(['bang'])
        end
      end

      context 'when the server selected does not support collations', unless: collation_enabled? do

        it 'raises an exception' do
          expect {
            result
          }.to raise_exception(Mongo::Error::UnsupportedCollation)
        end

        context 'when a String key is used' do

          let(:options) do
            { 'collation' => { locale: 'en_US', strength: 2 } }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end
        end
      end
    end

    context 'when a collation is not specified' do

      let(:result) do
        authorized_collection.distinct(:name)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
        authorized_collection.insert_one(name: 'BANG')
      end

      it 'does not apply the collation to the distinct' do
        expect(result).to match_array(['bang', 'BANG'])
      end
    end
  end

  describe '#delete_one' do

    context 'when a selector was provided' do

      let(:selector) do
        { field: 'test1' }
      end

      before do
        authorized_collection.insert_many([
                                            { field: 'test1' },
                                            { field: 'test1' },
                                            { field: 'test1' }
                                          ])
      end

      let(:response) do
        authorized_collection.delete_one(selector)
      end

      it 'deletes the first matching document in the collection' do
        expect(response.deleted_count).to eq(1)
      end
    end

    context 'when no selector was provided' do

      before do
        authorized_collection.insert_many([{ field: 'test1' }, { field: 'test2' }])
      end

      let(:response) do
        authorized_collection.delete_one
      end

      it 'deletes the first document in the collection' do
        expect(response.deleted_count).to eq(1)
      end
    end

    context 'when the delete fails', if: standalone? do

      let(:result) do
        collection_invalid_write_concern.delete_one
      end

      it 'raises an OperationFailure' do
        expect {
          result
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when a session is provided' do

      let(:session) do
        authorized_client.start_session
      end

      let(:operation) do
        authorized_collection.delete_one({}, session: session)
      end

      let(:failed_operation) do
        authorized_collection.delete_one({ '$._id' => 1}, session: session)
      end

      let(:client) do
        authorized_client
      end

      it_behaves_like 'an operation using a session'
      it_behaves_like 'a failed operation using a session'
    end

    context 'when unacknowledged writes is used' do

      let(:collection_with_unacknowledged_write_concern) do
        authorized_collection.with(write: { w: 0 })
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.delete_one({}, session: session)
      end

      it_behaves_like 'an explicit session with an unacknowledged write'
    end

    context 'when unacknowledged writes is used with an implicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        subscribed_client.with(write: { w: 0 })[TEST_COLL]
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.delete_one
      end

      it_behaves_like 'an implicit session with an unacknowledged write'
    end

    context 'when a collation is provided' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.delete_one(selector, options)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      let(:options) do
        { collation: { locale: 'en_US', strength: 2 } }
      end

      context 'when the server selected supports collations', if: collation_enabled? do

        it 'applies the collation' do
          expect(result.written_count).to eq(1)
          expect(authorized_collection.find(name: 'bang').count).to eq(0)
        end

        context 'when unacknowledged writes is used' do

          let(:collection_with_unacknowledged_write_concern) do
            authorized_collection.with(write: { w: 0 })
          end

          let(:result) do
            collection_with_unacknowledged_write_concern.delete_one(selector, options)
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end

          context 'when a String key is used' do

            let(:options) do
              { 'collation' => { locale: 'en_US', strength: 2 } }
            end

            it 'raises an exception' do
              expect {
                result
              }.to raise_exception(Mongo::Error::UnsupportedCollation)
            end
          end
        end
      end

      context 'when the server selected does not support collations', unless: collation_enabled? do

        it 'raises an exception' do
          expect {
            result
          }.to raise_exception(Mongo::Error::UnsupportedCollation)
        end

        context 'when a String key is used' do

          let(:options) do
            { 'collation' => { locale: 'en_US', strength: 2 } }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end
        end
      end
    end

    context 'when collation is not specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.delete_one(selector)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      it 'does not apply the collation' do
        expect(result.written_count).to eq(0)
        expect(authorized_collection.find(name: 'bang').count).to eq(1)
      end
    end
  end

  describe '#delete_many' do

    before do
      authorized_collection.insert_many([{ field: 'test1' }, { field: 'test2' }])
    end

    context 'when a selector was provided' do

      let(:selector) do
        { field: 'test1' }
      end

      it 'deletes the matching documents in the collection' do
        expect(authorized_collection.delete_many(selector).deleted_count).to eq(1)
      end
    end

    context 'when no selector was provided' do

      it 'deletes all the documents in the collection' do
        expect(authorized_collection.delete_many.deleted_count).to eq(2)
      end
    end

    context 'when the deletes fail', if: standalone?  do

      let(:result) do
        collection_invalid_write_concern.delete_many
      end

      it 'raises an OperationFailure' do
        expect {
          result
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when a session is provided' do

      let(:session) do
        authorized_client.start_session
      end

      let(:operation) do
        authorized_collection.delete_many({}, session: session)
      end

      let(:failed_operation) do
        authorized_collection.delete_many({ '$._id' => 1}, session: session)
      end

      let(:client) do
        authorized_client
      end

      it_behaves_like 'an operation using a session'
      it_behaves_like 'a failed operation using a session'
    end

    context 'when unacknowledged writes is used with an explicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        authorized_collection.with(write: { w: 0 })
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.delete_many({ '$._id' => 1}, session: session)
      end

      it_behaves_like 'an explicit session with an unacknowledged write'
    end

    context 'when unacknowledged writes is used with an implicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        subscribed_client.with(write: { w: 0 })[TEST_COLL]
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.delete_many({ '$._id' => 1 })
      end

      it_behaves_like 'an implicit session with an unacknowledged write'
    end

    context 'when a collation is specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.delete_many(selector, options)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
        authorized_collection.insert_one(name: 'bang')
      end

      let(:options) do
        { collation: { locale: 'en_US', strength: 2 } }
      end

      context 'when the server selected supports collations', if: collation_enabled? do

        it 'applies the collation' do
          expect(result.written_count).to eq(2)
          expect(authorized_collection.find(name: 'bang').count).to eq(0)
        end

        context 'when unacknowledged writes is used' do

          let(:collection_with_unacknowledged_write_concern) do
            authorized_collection.with(write: { w: 0 })
          end

          let(:result) do
            collection_with_unacknowledged_write_concern.delete_many(selector, options)
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end

          context 'when a String key is used' do

            let(:options) do
              { 'collation' => { locale: 'en_US', strength: 2 } }
            end

            it 'raises an exception' do
              expect {
                result
              }.to raise_exception(Mongo::Error::UnsupportedCollation)
            end
          end
        end
      end

      context 'when the server selected does not support collations', unless: collation_enabled? do

        it 'raises an exception' do
          expect {
            result
          }.to raise_exception(Mongo::Error::UnsupportedCollation)
        end

        context 'when a String key is used' do

          let(:options) do
            { 'collation' => { locale: 'en_US', strength: 2 } }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end
        end
      end
    end

    context 'when a collation is not specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.delete_many(selector)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
        authorized_collection.insert_one(name: 'bang')
      end

      it 'does not apply the collation' do
        expect(result.written_count).to eq(0)
        expect(authorized_collection.find(name: 'bang').count).to eq(2)
      end
    end
  end

  describe '#parallel_scan', unless: sharded? do
    max_server_version '4.0'

    let(:documents) do
      (1..200).map do |i|
        { name: "testing-scan-#{i}" }
      end
    end

    before do
      authorized_collection.insert_many(documents)
    end

    let(:cursors) do
      authorized_collection.parallel_scan(2)
    end

    it 'returns an array of cursors' do
      cursors.each do |cursor|
        expect(cursor.class).to be(Mongo::Cursor)
      end
    end

    it 'returns the correct number of documents' do
      expect(
        cursors.reduce(0) { |total, cursor| total + cursor.to_a.size }
      ).to eq(200)
    end

    context 'when a session is provided' do

      let(:cursors) do
        authorized_collection.parallel_scan(2, session: session)
      end

      let(:operation) do
        cursors.reduce(0) { |total, cursor| total + cursor.to_a.size }
      end

      let(:failed_operation) do
        authorized_collection.parallel_scan(-2, session: session)
      end

      let(:client) do
        authorized_client
      end

      it_behaves_like 'an operation using a session'
      it_behaves_like 'a failed operation using a session'
    end

    context 'when a session is not provided' do
      let(:client) { subscribed_client }
      let(:collection) { client['test'] }

      let(:cursors) do
        collection.parallel_scan(2)
      end

      let(:operation) do
        cursors.reduce(0) { |total, cursor| total + cursor.to_a.size }
      end

      let(:failed_operation) do
        collection.parallel_scan(-2)
      end

      let(:command) do
        operation
        event = EventSubscriber.started_events.find { |cmd| cmd.command_name == 'parallelCollectionScan' }
        expect(event).not_to be_nil
        event.command
      end

      it_behaves_like 'an operation not using a session'
      it_behaves_like 'a failed operation not using a session'
    end

    context 'when a session supporting causal consistency is used' do

      let(:cursors) do
        collection.parallel_scan(2, session: session)
      end

      let(:operation) do
        cursors.reduce(0) { |total, cursor| total + cursor.to_a.size }
      end

      let(:command) do
        operation
        event = EventSubscriber.started_events.find { |cmd| cmd.command_name == 'parallelCollectionScan' }
        expect(event).not_to be_nil
        event.command
      end

      it_behaves_like 'an operation supporting causally consistent reads'
    end

    context 'when a read concern is provided' do
      min_server_version '3.2'

      let(:result) do
        authorized_collection.with(options).parallel_scan(2)
      end

      context 'when the read concern is valid' do

        let(:options) do
          { read_concern: { level: 'local' }}
        end

        it 'sends the read concern' do
          expect { result }.to_not raise_error
        end
      end

      context 'when the read concern is not valid' do

        let(:options) do
          { read_concern: { level: 'idontknow' }}
        end

        it 'raises an exception' do
          expect {
            result
          }.to raise_error(Mongo::Error::OperationFailure)
        end
      end
    end

    context 'when the collection has a read preference', unless: sharded? do

      before do
        allow(collection.client.cluster).to receive(:single?).and_return(false)
      end

      after do
        client.close
      end

      let(:client) do
        authorized_client.with(server_selection_timeout: 0.2)
      end

      let(:collection) do
        client[authorized_collection.name,
               read: { :mode => :secondary, :tag_sets => [{ 'non' => 'existent' }] }]
      end

      let(:result) do
        collection.parallel_scan(2)
      end

      it 'uses that read preference' do
        expect {
          result
        }.to raise_exception(Mongo::Error::NoServerAvailable)
      end
    end

    context 'when a max time ms value is provided', if: !sharded? do

      let(:result) do
        authorized_collection.parallel_scan(2, options)
      end

      context 'when the read concern is valid' do

        let(:options) do
          { max_time_ms: 5 }
        end

        it 'sends the max time ms value' do
          expect { result }.to_not raise_error
        end
      end

      context 'when the max time ms is not valid' do

        let(:options) do
          { max_time_ms: 0.1 }
        end

        it 'raises an exception' do
          expect {
            result
          }.to raise_error(Mongo::Error::OperationFailure)
        end
      end
    end
  end

  describe '#replace_one' do

    let(:selector) do
      { field: 'test1' }
    end

    context 'when a selector was provided' do

      before do
        authorized_collection.insert_many([{ field: 'test1' }, { field: 'test1' }])
      end

      let!(:response) do
        authorized_collection.replace_one(selector, { field: 'testing' })
      end

      let(:updated) do
        authorized_collection.find(field: 'testing').first
      end

      it 'updates the first matching document in the collection' do
        expect(response.modified_count).to eq(1)
      end

      it 'updates the documents in the collection' do
        expect(updated[:field]).to eq('testing')
      end
    end

    context 'when upsert is false' do

      let!(:response) do
        authorized_collection.replace_one(selector, { field: 'test1' }, upsert: false)
      end

      let(:updated) do
        authorized_collection.find(field: 'test1').to_a
      end

      it 'reports that no documents were written'  do
        expect(response.modified_count).to eq(0)
      end

      it 'does not insert the document' do
        expect(updated).to be_empty
      end
    end

    context 'when upsert is true' do

      let!(:response) do
        authorized_collection.replace_one(selector, { field: 'test1' }, upsert: true)
      end

      let(:updated) do
        authorized_collection.find(field: 'test1').first
      end

      it 'reports that a document was written' do
        expect(response.written_count).to eq(1)
      end

      it 'inserts the document' do
        expect(updated[:field]).to eq('test1')
      end
    end

    context 'when upsert is not specified' do

      let!(:response) do
        authorized_collection.replace_one(selector, { field: 'test1' })
      end

      let(:updated) do
        authorized_collection.find(field: 'test1').to_a
      end

      it 'reports that no documents were written' do
        expect(response.modified_count).to eq(0)
      end

      it 'does not insert the document' do
        expect(updated).to be_empty
      end
    end

    context 'when the replace fails' do

      let(:result) do
        authorized_collection.replace_one(selector, { '$s' => 'test1' })
      end

      it 'raises an OperationFailure' do
        expect {
          result
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when collection has a validator' do
      min_server_version '3.2'

      around(:each) do |spec|
        authorized_client[:validating,
                          :validator => { :a => { '$exists' => true } }].tap do |c|
          c.create
        end
        spec.run
        collection_with_validator.drop
      end

      before do
        collection_with_validator.insert_one({ a: 1 })
      end

      context 'when the document is valid' do

        let(:result) do
          collection_with_validator.replace_one({ a: 1 }, { a: 5 })
        end

        it 'replaces successfully' do
          expect(result.modified_count).to eq(1)
        end
      end

      context 'when the document is invalid' do

        context 'when bypass_document_validation is not set' do

          let(:result2) do
            collection_with_validator.replace_one({ a: 1 }, { x: 5 })
          end

          it 'raises OperationFailure' do
            expect {
              result2
            }.to raise_exception(Mongo::Error::OperationFailure)
          end
        end

        context 'when bypass_document_validation is true' do

          let(:result3) do
            collection_with_validator.replace_one(
              { a: 1 }, { x: 1 }, :bypass_document_validation => true)
          end

          it 'replaces successfully' do
            expect(result3.written_count).to eq(1)
          end
        end
      end
    end

    context 'when a collation is specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.replace_one(selector, { name: 'doink' }, options)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      let(:options) do
        { collation: { locale: 'en_US', strength: 2 } }
      end

      context 'when the server selected supports collations', if: collation_enabled? do

        it 'applies the collation' do
          expect(result.written_count).to eq(1)
          expect(authorized_collection.find(name: 'doink').count).to eq(1)
        end

        context 'when unacknowledged writes is used' do

          let(:collection_with_unacknowledged_write_concern) do
            authorized_collection.with(write: { w: 0 })
          end

          let(:result) do
            collection_with_unacknowledged_write_concern.replace_one(selector, { name: 'doink' }, options)
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end

          context 'when a String key is used' do

            let(:options) do
              { 'collation' => { locale: 'en_US', strength: 2 } }
            end

            it 'raises an exception' do
              expect {
                result
              }.to raise_exception(Mongo::Error::UnsupportedCollation)
            end
          end
        end
      end

      context 'when the server selected does not support collations', unless: collation_enabled? do

        it 'raises an exception' do
          expect {
            result
          }.to raise_exception(Mongo::Error::UnsupportedCollation)
        end

        context 'when a String key is used' do

          let(:options) do
            { 'collation' => { locale: 'en_US', strength: 2 } }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end
        end
      end
    end

    context 'when a collation is not specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.replace_one(selector, { name: 'doink' })
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      it 'does not apply the collation' do
        expect(result.written_count).to eq(0)
        expect(authorized_collection.find(name: 'bang').count).to eq(1)
      end
    end

    context 'when a session is provided' do

      let(:selector) do
        { name: 'BANG' }
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      let(:session) do
        authorized_client.start_session
      end

      let(:operation) do
        authorized_collection.replace_one(selector, { name: 'doink' }, session: session)
      end

      let(:failed_operation) do
        authorized_collection.replace_one({ '$._id' => 1 }, { name: 'doink' }, session: session)
      end

      let(:client) do
        authorized_client
      end

      it_behaves_like 'an operation using a session'
      it_behaves_like 'a failed operation using a session'
    end

    context 'when unacknowledged writes is used with an explicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        authorized_collection.with(write: { w: 0 })
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.replace_one({ a: 1 }, { x: 5 }, session: session)
      end

      it_behaves_like 'an explicit session with an unacknowledged write'
    end

    context 'when unacknowledged writes is used with an implicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        subscribed_client.with(write: { w: 0 })[TEST_COLL]
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.replace_one({ a: 1 }, { x: 5 })
      end

      it_behaves_like 'an implicit session with an unacknowledged write'
    end
  end

  describe '#update_many' do

    let(:selector) do
      { field: 'test' }
    end

    context 'when a selector was provided' do

      before do
        authorized_collection.insert_many([{ field: 'test' }, { field: 'test' }])
      end

      let!(:response) do
        authorized_collection.update_many(selector, '$set'=> { field: 'testing' })
      end

      let(:updated) do
        authorized_collection.find(field: 'testing').to_a.last
      end

      it 'returns the number updated' do
        expect(response.modified_count).to eq(2)
      end

      it 'updates the documents in the collection' do
        expect(updated[:field]).to eq('testing')
      end
    end

    context 'when upsert is false' do

      let(:response) do
        authorized_collection.update_many(selector, { '$set'=> { field: 'testing' } },
                                          upsert: false)
      end

      let(:updated) do
        authorized_collection.find.to_a
      end

      it 'reports that no documents were updated' do
        expect(response.modified_count).to eq(0)
      end

      it 'updates no documents in the collection' do
        expect(updated).to be_empty
      end
    end

    context 'when upsert is true' do

      let!(:response) do
        authorized_collection.update_many(selector, { '$set'=> { field: 'testing' } },
                                          upsert: true)
      end

      let(:updated) do
        authorized_collection.find.to_a.last
      end

      it 'reports that a document was written' do
        expect(response.written_count).to eq(1)
      end

      it 'inserts a document into the collection' do
        expect(updated[:field]).to eq('testing')
      end
    end

    context 'when upsert is not specified' do

      let(:response) do
        authorized_collection.update_many(selector, { '$set'=> { field: 'testing' } })
      end

      let(:updated) do
        authorized_collection.find.to_a
      end

      it 'reports that no documents were updated' do
        expect(response.modified_count).to eq(0)
      end

      it 'updates no documents in the collection' do
        expect(updated).to be_empty
      end
    end

    context 'when arrayFilters is provided' do

      let(:selector) do
        { '$or' => [{ _id: 0 }, { _id: 1 }]}
      end

      context 'when the server supports arrayFilters', if: array_filters_enabled? do

        before do
          authorized_collection.insert_many([{
                                               _id: 0, x: [
                                                 { y: 1 },
                                                 { y: 2 },
                                                 { y: 3 }
                                               ]
                                             },
                                             {
                                               _id: 1,
                                               x: [
                                                 { y: 3 },
                                                 { y: 2 },
                                                 { y: 1 }
                                               ]
                                             }])
        end

        let(:result) do
          authorized_collection.update_many(selector,
                                            { '$set' => { 'x.$[i].y' => 5 } },
                                            options)
        end

        context 'when a Symbol key is used' do

          let(:options) do
            { array_filters: [{ 'i.y' => 3 }] }
          end

          it 'applies the arrayFilters' do
            expect(result.matched_count).to eq(2)
            expect(result.modified_count).to eq(2)

            docs = authorized_collection.find(selector, sort: { _id: 1 }).to_a
            expect(docs[0]['x']).to eq ([{ 'y' => 1 },  { 'y' => 2 }, { 'y' => 5 }])
            expect(docs[1]['x']).to eq ([{ 'y' => 5 },  { 'y' => 2 }, { 'y' => 1 }])
          end
        end

        context 'when a String key is used' do
          let(:options) do
            { 'array_filters' => [{ 'i.y' => 3 }] }
          end

          it 'applies the arrayFilters' do
            expect(result.matched_count).to eq(2)
            expect(result.modified_count).to eq(2)

            docs = authorized_collection.find({}, sort: { _id: 1 }).to_a
            expect(docs[0]['x']).to eq ([{ 'y' => 1 },  { 'y' => 2 }, { 'y' => 5 }])
            expect(docs[1]['x']).to eq ([{ 'y' => 5 },  { 'y' => 2 }, { 'y' => 1 }])
          end
        end
      end

      context 'when the server does not support arrayFilters', unless: array_filters_enabled? do

        let(:result) do
          authorized_collection.update_many(selector,
                                           { '$set' => { 'x.$[i].y' => 5 } },
                                           options)
        end

        context 'when a Symbol key is used' do

          let(:options) do
            { array_filters: [{ 'i.y' => 3 }] }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedArrayFilters)
          end
        end

        context 'when a String key is used' do

          let(:options) do
            { 'array_filters' => [{ 'i.y' => 3 }] }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedArrayFilters)
          end
        end
      end
    end

    context 'when the updates fail' do

      let(:result) do
        authorized_collection.update_many(selector, { '$s'=> { field: 'testing' } })
      end

      it 'raises an OperationFailure' do
        expect {
          result
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when collection has a validator' do
      min_server_version '3.2'

      around(:each) do |spec|
        authorized_client[:validating,
                          :validator => { :a => { '$exists' => true } }].tap do |c|
          c.create
        end
        spec.run
        collection_with_validator.drop
      end

      before do
        collection_with_validator.insert_many([{ a: 1 }, { a: 2 }])
      end

      context 'when the document is valid' do

        let(:result) do
          collection_with_validator.update_many(
            { :a => { '$gt' => 0 } }, '$inc' => { :a => 1 } )
        end

        it 'updates successfully' do
          expect(result.modified_count).to eq(2)
        end
      end

      context 'when the document is invalid' do

        context 'when bypass_document_validation is not set' do

          let(:result2) do
            collection_with_validator.update_many(
              { :a => { '$gt' => 0 } }, '$unset' => { :a => '' })
          end

          it 'raises OperationFailure' do
            expect {
              result2
            }.to raise_exception(Mongo::Error::OperationFailure)
          end
        end

        context 'when bypass_document_validation is true' do

          let(:result3) do
            collection_with_validator.update_many(
              { :a => { '$gt' => 0 } }, { '$unset' => { :a => '' } },
              :bypass_document_validation => true)
          end

          it 'updates successfully' do
            expect(result3.written_count).to eq(2)
          end
        end
      end
    end

    context 'when a collation is specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.update_many(selector, { '$set' => { other: 'doink' } }, options)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
        authorized_collection.insert_one(name: 'baNG')
      end

      let(:options) do
        { collation: { locale: 'en_US', strength: 2 } }
      end

      context 'when the server selected supports collations', if: collation_enabled? do

        it 'applies the collation' do
          expect(result.written_count).to eq(2)
          expect(authorized_collection.find(other: 'doink').count).to eq(2)
        end

        context 'when unacknowledged writes is used' do

          let(:collection_with_unacknowledged_write_concern) do
            authorized_collection.with(write: { w: 0 })
          end

          let(:result) do
            collection_with_unacknowledged_write_concern.update_many(selector, { '$set' => { other: 'doink' } }, options)
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end

          context 'when a String key is used' do

            let(:options) do
              { 'collation' => { locale: 'en_US', strength: 2 } }
            end

            it 'raises an exception' do
              expect {
                result
              }.to raise_exception(Mongo::Error::UnsupportedCollation)
            end
          end
        end
      end

      context 'when the server selected does not support collations', unless: collation_enabled? do

        it 'raises an exception' do
          expect {
            result
          }.to raise_exception(Mongo::Error::UnsupportedCollation)
        end

        context 'when a String key is used' do

          let(:options) do
            { 'collation' => { locale: 'en_US', strength: 2 } }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end
        end
      end
    end

    context 'when collation is not specified' do

      let(:selector) do
        {name: 'BANG'}
      end

      let(:result) do
        authorized_collection.update_many(selector, { '$set' => {other: 'doink'} })
      end

      before do
        authorized_collection.insert_one(name: 'bang')
        authorized_collection.insert_one(name: 'baNG')
      end

      it 'does not apply the collation' do
        expect(result.written_count).to eq(0)
      end
    end

    context 'when a session is provided' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:operation) do
        authorized_collection.update_many(selector, { '$set' => {other: 'doink'} }, session: session)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
        authorized_collection.insert_one(name: 'baNG')
      end

      let(:session) do
        authorized_client.start_session
      end

      let(:failed_operation) do
        authorized_collection.update_many({ '$._id' => 1 }, { '$set' => {other: 'doink'} }, session: session)
      end

      let(:client) do
        authorized_client
      end

      it_behaves_like 'an operation using a session'
      it_behaves_like 'a failed operation using a session'
    end

    context 'when unacknowledged writes is used with an explicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        authorized_collection.with(write: { w: 0 })
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.update_many({a: 1}, { '$set' => {x: 1} }, session: session)
      end

      it_behaves_like 'an explicit session with an unacknowledged write'
    end

    context 'when unacknowledged writes is used with an implicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        subscribed_client.with(write: { w: 0 })[TEST_COLL]
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.update_many({a: 1}, {'$set' => {x: 1}})
      end

      it_behaves_like 'an implicit session with an unacknowledged write'
    end
  end

  describe '#update_one' do

    let(:selector) do
      { field: 'test1' }
    end

    context 'when a selector was provided' do

      before do
        authorized_collection.insert_many([{ field: 'test1' }, { field: 'test1' }])
      end

      let!(:response) do
        authorized_collection.update_one(selector, '$set'=> { field: 'testing' })
      end

      let(:updated) do
        authorized_collection.find(field: 'testing').first
      end

      it 'updates the first matching document in the collection' do
        expect(response.modified_count).to eq(1)
      end

      it 'updates the documents in the collection' do
        expect(updated[:field]).to eq('testing')
      end
    end

    context 'when upsert is false' do

      let(:response) do
        authorized_collection.update_one(selector, { '$set'=> { field: 'testing' } },
                                         upsert: false)
      end

      let(:updated) do
        authorized_collection.find.to_a
      end

      it 'reports that no documents were updated' do
        expect(response.modified_count).to eq(0)
      end

      it 'updates no documents in the collection' do
        expect(updated).to be_empty
      end
    end

    context 'when upsert is true' do

      let!(:response) do
        authorized_collection.update_one(selector, { '$set'=> { field: 'testing' } },
                                         upsert: true)
      end

      let(:updated) do
        authorized_collection.find.first
      end

      it 'reports that a document was written' do
        expect(response.written_count).to eq(1)
      end

      it 'inserts a document into the collection' do
        expect(updated[:field]).to eq('testing')
      end
    end

    context 'when upsert is not specified' do

      let(:response) do
        authorized_collection.update_one(selector, { '$set'=> { field: 'testing' } })
      end

      let(:updated) do
        authorized_collection.find.to_a
      end

      it 'reports that no documents were updated' do
        expect(response.modified_count).to eq(0)
      end

      it 'updates no documents in the collection' do
        expect(updated).to be_empty
      end
    end

    context 'when the update fails' do

      let(:result) do
        authorized_collection.update_one(selector, { '$s'=> { field: 'testing' } })
      end

      it 'raises an OperationFailure' do
        expect {
          result
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when collection has a validator' do
      min_server_version '3.2'

      around(:each) do |spec|
        authorized_client[:validating,
                          :validator => { :a => { '$exists' => true } }].tap do |c|
          c.create
        end
        spec.run
        collection_with_validator.drop
      end

      before do
        collection_with_validator.insert_one({ a: 1 })
      end

      context 'when the document is valid' do

        let(:result) do
          collection_with_validator.update_one(
            { :a => { '$gt' => 0 } }, '$inc' => { :a => 1 } )
        end

        it 'updates successfully' do
          expect(result.modified_count).to eq(1)
        end
      end

      context 'when the document is invalid' do

        context 'when bypass_document_validation is not set' do

          let(:result2) do
            collection_with_validator.update_one(
              { :a => { '$gt' => 0 } }, '$unset' => { :a => '' })
          end

          it 'raises OperationFailure' do
            expect {
              result2
            }.to raise_exception(Mongo::Error::OperationFailure)
          end
        end

        context 'when bypass_document_validation is true' do

          let(:result3) do
            collection_with_validator.update_one(
              { :a => { '$gt' => 0 } }, { '$unset' => { :a => '' } },
              :bypass_document_validation => true)
          end

          it 'updates successfully' do
            expect(result3.written_count).to eq(1)
          end
        end
      end
    end

    context 'when there is a collation specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.update_one(selector, { '$set' => { other: 'doink' } }, options)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      let(:options) do
        { collation: { locale: 'en_US', strength: 2 } }
      end

      context 'when the server selected supports collations', if: collation_enabled? do

        it 'applies the collation' do
          expect(result.written_count).to eq(1)
          expect(authorized_collection.find(other: 'doink').count).to eq(1)
        end

        context 'when unacknowledged writes is used' do

          let(:collection_with_unacknowledged_write_concern) do
            authorized_collection.with(write: { w: 0 })
          end

          let(:result) do
            collection_with_unacknowledged_write_concern.update_one(selector, { '$set' => { other: 'doink' } }, options)
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end

          context 'when a String key is used' do

            let(:options) do
              { 'collation' => { locale: 'en_US', strength: 2 } }
            end

            it 'raises an exception' do
              expect {
                result
              }.to raise_exception(Mongo::Error::UnsupportedCollation)
            end
          end
        end
      end

      context 'when the server selected does not support collations', unless: collation_enabled? do

        it 'raises an exception' do
          expect {
            result
          }.to raise_exception(Mongo::Error::UnsupportedCollation)
        end

        context 'when a String key is used' do

          let(:options) do
            { 'collation' => { locale: 'en_US', strength: 2 } }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end
        end
      end
    end

    context 'when a collation is not specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.update_one(selector, { '$set' => { other: 'doink' } })
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      it 'does not apply the collation' do
        expect(result.written_count).to eq(0)
      end
    end


    context 'when arrayFilters is provided' do

      let(:selector) do
        { _id: 0}
      end

      context 'when the server supports arrayFilters', if: array_filters_enabled? do

        before do
          authorized_collection.insert_one(_id: 0, x: [{ y: 1 }, { y: 2 }, {y: 3 }])
        end

        let(:result) do
          authorized_collection.update_one(selector,
                                           { '$set' => { 'x.$[i].y' => 5 } },
                                           options)
        end

        context 'when a Symbol key is used' do

          let(:options) do
            { array_filters: [{ 'i.y' => 3 }] }
          end

          it 'applies the arrayFilters' do
            expect(result.matched_count).to eq(1)
            expect(result.modified_count).to eq(1)
            expect(authorized_collection.find(selector).first['x'].last['y']).to eq(5)
          end
        end

        context 'when a String key is used' do

          let(:options) do
            { 'array_filters' => [{ 'i.y' => 3 }] }
          end

          it 'applies the arrayFilters' do
            expect(result.matched_count).to eq(1)
            expect(result.modified_count).to eq(1)
            expect(authorized_collection.find(selector).first['x'].last['y']).to eq(5)
          end
        end
      end

      context 'when the server does not support arrayFilters', unless: array_filters_enabled? do

        let(:result) do
          authorized_collection.update_one(selector,
                                           { '$set' => { 'x.$[i].y' => 5 } },
                                           options)
        end

        context 'when a Symbol key is used' do

          let(:options) do
            { array_filters: [{ 'i.y' => 3 }] }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedArrayFilters)
          end
        end

        context 'when a String key is used' do

          let(:options) do
            { 'array_filters' => [{ 'i.y' => 3 }] }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedArrayFilters)
          end
        end
      end
    end

    context 'when the documents are sent with OP_MSG' do
      min_server_version '3.6'

      let(:client) do
        subscribed_client
      end

      let(:documents) do
        [{ '_id' => 1, 'name' => '1'*16777191 }, { '_id' => 'y' }]
      end

      before do
        authorized_collection.insert_many([{ field: 'test1' }, { field: 'test1' }])
        client[TEST_COLL].update_one({ a: 1 }, {'$set' => { 'name' => '1'*16777149 }})
      end

      after do
        client.close
      end

      let(:update_events) do
        EventSubscriber.started_events.select { |e| e.command_name == 'update' }
      end

      it 'sends the documents in one OP_MSG' do
        expect(update_events.size).to eq(1)
      end
    end

    context 'when a session is provided' do

      before do
        authorized_collection.insert_many([{ field: 'test1' }, { field: 'test1' }])
      end

      let(:session) do
        authorized_client.start_session
      end

      let(:operation) do
        authorized_collection.update_one({ field: 'test' }, { '$set'=> { field: 'testing' } }, session: session)
      end

      let(:failed_operation) do
        authorized_collection.update_one({ '$._id' => 1 }, { '$set'=> { field: 'testing' } }, session: session)
      end

      let(:client) do
        authorized_client
      end

      it_behaves_like 'an operation using a session'
      it_behaves_like 'a failed operation using a session'
    end

    context 'when unacknowledged writes is used with an explicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        authorized_collection.with(write: { w: 0 })
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.update_one({ a: 1 }, { '$set' => { x: 1 } }, session: session)
      end

      it_behaves_like 'an explicit session with an unacknowledged write'
    end

    context 'when unacknowledged writes is used with an implicit session' do

      let(:collection_with_unacknowledged_write_concern) do
        subscribed_client.with(write: { w: 0 })[TEST_COLL]
      end

      let(:operation) do
        collection_with_unacknowledged_write_concern.update_one({ a: 1 }, { '$set' => { x: 1 }})
      end

      it_behaves_like 'an implicit session with an unacknowledged write'
    end
  end

  describe '#find_one_and_delete' do

    before do
      authorized_collection.insert_many([{ field: 'test1' }])
    end

    let(:selector) do
      { field: 'test1' }
    end

    context 'when a matching document is found' do

      context 'when a session is provided' do

        let(:operation) do
          authorized_collection.find_one_and_delete(selector, session: session)
        end

        let(:failed_operation) do
          authorized_collection.find_one_and_delete({ '$._id' => 1 }, session: session)
        end

        let(:session) do
          authorized_client.start_session
        end

        let(:client) do
          authorized_client
        end

        it_behaves_like 'an operation using a session'
        it_behaves_like 'a failed operation using a session'
      end

      context 'when no options are provided' do

        let!(:document) do
          authorized_collection.find_one_and_delete(selector)
        end

        it 'deletes the document from the database' do
          expect(authorized_collection.find.to_a).to be_empty
        end

        it 'returns the document' do
          expect(document['field']).to eq('test1')
        end
      end

      context 'when a projection is provided' do

        let!(:document) do
          authorized_collection.find_one_and_delete(selector, projection: { _id: 1 })
        end

        it 'deletes the document from the database' do
          expect(authorized_collection.find.to_a).to be_empty
        end

        it 'returns the document with limited fields' do
          expect(document['field']).to be_nil
          expect(document['_id']).to_not be_nil
        end
      end

      context 'when a sort is provided' do

        let!(:document) do
          authorized_collection.find_one_and_delete(selector, sort: { field: 1 })
        end

        it 'deletes the document from the database' do
          expect(authorized_collection.find.to_a).to be_empty
        end

        it 'returns the document with limited fields' do
          expect(document['field']).to eq('test1')
        end
      end

      context 'when max_time_ms is provided' do

        it 'includes the max_time_ms value in the command' do
          expect {
            authorized_collection.find_one_and_delete(selector, max_time_ms: 0.1)
          }.to raise_error(Mongo::Error::OperationFailure)
        end
      end
    end

    context 'when no matching document is found' do

      let(:selector) do
        { field: 'test5' }
      end

      let!(:document) do
        authorized_collection.find_one_and_delete(selector)
      end

      it 'returns nil' do
        expect(document).to be_nil
      end
    end

    context 'when the operation fails' do

      let(:result) do
        authorized_collection.find_one_and_delete(selector, max_time_ms: 0.1)
      end

      it 'raises an OperationFailure' do
        expect {
          result
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when write_concern is provided', if: standalone? do
      min_server_version '3.2'

      it 'uses the write concern' do
        expect {
          authorized_collection.find_one_and_delete(selector,
                                                    write_concern: { w: 2 })
        }.to raise_error(Mongo::Error::OperationFailure)
      end
    end

    context 'when the collection has a write concern', if: standalone? do
      min_server_version '3.2'

      let(:collection) do
        authorized_collection.with(write: { w: 2 })
      end

      it 'uses the write concern' do
        expect {
          collection.find_one_and_delete(selector,
                                         write_concern: { w: 2 })
        }.to raise_error(Mongo::Error::OperationFailure)
      end
    end

    context 'when collation is specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.find_one_and_delete(selector, options)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      let(:options) do
        { collation: { locale: 'en_US', strength: 2 } }
      end

      context 'when the server selected supports collations', if: collation_enabled? do

        it 'applies the collation' do
          expect(result['name']).to eq('bang')
          expect(authorized_collection.find(name: 'bang').count).to eq(0)
        end
      end

      context 'when the server selected does not support collations', unless: collation_enabled? do

        it 'raises an exception' do
          expect {
            result
          }.to raise_exception(Mongo::Error::UnsupportedCollation)
        end

        context 'when a String key is used' do

          let(:options) do
            { 'collation' => { locale: 'en_US', strength: 2 } }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end
        end
      end
    end

    context 'when collation is not specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.find_one_and_delete(selector)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      it 'does not apply the collation' do
        expect(result).to be_nil
      end
    end
  end

  describe '#find_one_and_update' do

    let(:selector) do
      { field: 'test1' }
    end

    before do
      authorized_collection.insert_many([{ field: 'test1' }])
    end

    context 'when a matching document is found' do

      context 'when no options are provided' do

        let(:document) do
          authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }})
        end

        it 'returns the original document' do
          expect(document['field']).to eq('test1')
        end
      end

      context 'when a session is provided' do

        let(:operation) do
          authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }}, session: session)
        end

        let(:failed_operation) do
          authorized_collection.find_one_and_update({ '$._id' => 1 }, { '$set' => { field: 'testing' }}, session: session)
        end

        let(:session) do
          authorized_client.start_session
        end

        let(:client) do
          authorized_client
        end

        it_behaves_like 'an operation using a session'
        it_behaves_like 'a failed operation using a session'
      end

      context 'when no options are provided' do

        let(:document) do
          authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }})
        end

        it 'returns the original document' do
          expect(document['field']).to eq('test1')
        end
      end

      context 'when return_document options are provided' do

        context 'when return_document is :after' do

          let(:document) do
            authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }}, :return_document => :after)
          end

          it 'returns the new document' do
            expect(document['field']).to eq('testing')
          end
        end

        context 'when return_document is :before' do

          let(:document) do
            authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }}, :return_document => :before)
          end

          it 'returns the original document' do
            expect(document['field']).to eq('test1')
          end
        end
      end

      context 'when a projection is provided' do

        let(:document) do
          authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }}, projection: { _id: 1 })
        end

        it 'returns the document with limited fields' do
          expect(document['field']).to be_nil
          expect(document['_id']).to_not be_nil
        end
      end

      context 'when a sort is provided' do

        let(:document) do
          authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }}, sort: { field: 1 })
        end

        it 'returns the original document' do
          expect(document['field']).to eq('test1')
        end
      end
    end

    context 'when max_time_ms is provided' do

      it 'includes the max_time_ms value in the command' do
        expect {
          authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }}, max_time_ms: 0.1)
        }.to raise_error(Mongo::Error::OperationFailure)
      end
    end

    context 'when no matching document is found' do

      let(:selector) do
        { field: 'test5' }
      end

      let(:document) do
        authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }})
      end

      it 'returns nil' do
        expect(document).to be_nil
      end
    end

    context 'when no matching document is found' do

      context 'when no upsert options are provided' do

        let(:selector) do
          { field: 'test5' }
        end

        let(:document) do
          authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }})
        end

        it 'returns nil' do
          expect(document).to be_nil
        end
      end

      context 'when upsert options are provided' do

        let(:selector) do
          { field: 'test5' }
        end

        let(:document) do
          authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }}, :upsert => true, :return_document => :after)
        end

        it 'returns the new document' do
          expect(document['field']).to eq('testing')
        end
      end
    end

    context 'when the operation fails' do

      let(:result) do
        authorized_collection.find_one_and_update(selector, { '$set' => { field: 'testing' }}, max_time_ms: 0.1)
      end

      it 'raises an OperationFailure' do
        expect {
          result
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when collection has a validator' do
      min_server_version '3.2'

      around(:each) do |spec|
        authorized_client[:validating].drop
        authorized_client[:validating,
                          :validator => { :a => { '$exists' => true } }].tap do |c|
          c.create
        end
        spec.run
        collection_with_validator.drop
      end

      before do
        collection_with_validator.insert_one({ a: 1 })
      end

      context 'when the document is valid' do

        let(:result) do
          collection_with_validator.find_one_and_update(
            { a: 1 }, { '$inc' => { :a => 1 } }, :return_document => :after)
        end

        it 'updates successfully' do
          expect(result['a']).to eq(2)
        end
      end

      context 'when the document is invalid' do

        context 'when bypass_document_validation is not set' do

          let(:result2) do
            collection_with_validator.find_one_and_update(
              { a: 1 }, { '$unset' => { :a => '' } }, :return_document => :after)
          end

          it 'raises OperationFailure' do
            expect {
              result2
            }.to raise_exception(Mongo::Error::OperationFailure)
          end
        end

        context 'when bypass_document_validation is true' do

          let(:result3) do
            collection_with_validator.find_one_and_update(
              { a: 1 }, { '$unset' => { :a => '' } },
              :bypass_document_validation => true,
              :return_document => :after)
          end

          it 'updates successfully' do
            expect(result3['a']).to be_nil
          end
        end
      end
    end

    context 'when write_concern is provided', if: standalone? do
      min_server_version '3.2'

      it 'uses the write concern' do
        expect {
          authorized_collection.find_one_and_update(selector,
                                                    { '$set' => { field: 'testing' }},
                                                    write_concern: { w: 2 })
        }.to raise_error(Mongo::Error::OperationFailure)
      end
    end

    context 'when the collection has a write concern', if: standalone? do
      min_server_version '3.2'

      let(:collection) do
        authorized_collection.with(write: { w: 2 })
      end

      it 'uses the write concern' do
        expect {
          collection.find_one_and_update(selector,
                                         { '$set' => { field: 'testing' }},
                                         write_concern: { w: 2 })
        }.to raise_error(Mongo::Error::OperationFailure)
      end
    end

    context 'when a collation is specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.find_one_and_update(selector,
                                                  { '$set' => { other: 'doink' } },
                                                  options)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      let(:options) do
        { collation: { locale: 'en_US', strength: 2 } }
      end

      context 'when the server selected supports collations', if: collation_enabled? do

        it 'applies the collation' do
          expect(result['name']).to eq('bang')
          expect(authorized_collection.find({ name: 'bang' }, limit: -1).first['other']).to eq('doink')
        end
      end

      context 'when the server selected does not support collations', unless: collation_enabled? do

        it 'raises an exception' do
          expect {
            result
          }.to raise_exception(Mongo::Error::UnsupportedCollation)
        end

        context 'when a String key is used' do

          let(:options) do
            { 'collation' => { locale: 'en_US', strength: 2 } }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end
        end
      end
    end

    context 'when there is no collation specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.find_one_and_update(selector, { '$set' => { other: 'doink' } })
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      it 'does not apply the collation' do
        expect(result).to be_nil
      end
    end

    context 'when arrayFilters is provided' do

      let(:selector) do
        { _id: 0 }
      end

      context 'when the server supports arrayFilters', if: array_filters_enabled? do

        before do
          authorized_collection.insert_one(_id: 0, x: [{ y: 1 }, { y: 2 }, { y: 3 }])
        end

        let(:result) do
          authorized_collection.find_one_and_update(selector,
                                                    { '$set' => { 'x.$[i].y' => 5 } },
                                                    options)
        end

        context 'when a Symbol key is used' do

          let(:options) do
            { array_filters: [{ 'i.y' => 3 }] }
          end


          it 'applies the arrayFilters' do
            expect(result['x']).to eq([{ 'y' => 1 }, { 'y' => 2 }, { 'y' => 3 }])
            expect(authorized_collection.find(selector).first['x'].last['y']).to eq(5)
          end
        end

        context 'when a String key is used' do

          let(:options) do
            { 'array_filters' => [{ 'i.y' => 3 }] }
          end

          it 'applies the arrayFilters' do
            expect(result['x']).to eq([{ 'y' => 1 }, { 'y' => 2 }, { 'y' => 3 }])
            expect(authorized_collection.find(selector).first['x'].last['y']).to eq(5)
          end
        end
      end

      context 'when the server selected does not support arrayFilters', unless: array_filters_enabled? do

        let(:result) do
          authorized_collection.find_one_and_update(selector,
                                                    { '$set' => { 'x.$[i].y' => 5 } },
                                                    options)
        end

        context 'when a Symbol key is used' do

          let(:options) do
            { array_filters: [{ 'i.y' => 3 }] }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedArrayFilters)
          end
        end

        context 'when a String key is used' do

          let(:options) do
            { 'array_filters' => [{ 'i.y' => 3 }] }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedArrayFilters)
          end
        end
      end
    end
  end

  describe '#find_one_and_replace' do

    before do
      authorized_collection.insert_many([{ field: 'test1', other: 'sth' }])
    end

    let(:selector) do
      { field: 'test1' }
    end

    context 'when a matching document is found' do

      context 'when no options are provided' do

        let(:document) do
          authorized_collection.find_one_and_replace(selector, { field: 'testing' })
        end

        it 'returns the original document' do
          expect(document['field']).to eq('test1')
        end
      end

      context 'when a session is provided' do

        let(:operation) do
          authorized_collection.find_one_and_replace(selector, { field: 'testing' }, session: session)
        end

        let(:failed_operation) do
          authorized_collection.find_one_and_replace({ '$._id' => 1}, { field: 'testing' }, session: session)
        end

        let(:session) do
          authorized_client.start_session
        end

        let(:client) do
          authorized_client
        end

        it_behaves_like 'an operation using a session'
        it_behaves_like 'a failed operation using a session'
      end

      context 'when return_document options are provided' do

        context 'when return_document is :after' do

          let(:document) do
            authorized_collection.find_one_and_replace(selector, { field: 'testing' }, :return_document => :after)
          end

          it 'returns the new document' do
            expect(document['field']).to eq('testing')
          end
        end

        context 'when return_document is :before' do

          let(:document) do
            authorized_collection.find_one_and_replace(selector, { field: 'testing' }, :return_document => :before)
          end

          it 'returns the original document' do
            expect(document['field']).to eq('test1')
          end
        end
      end

      context 'when a projection is provided' do

        let(:document) do
          authorized_collection.find_one_and_replace(selector, { field: 'testing' }, projection: { _id: 1 })
        end

        it 'returns the document with limited fields' do
          expect(document['field']).to be_nil
          expect(document['_id']).to_not be_nil
        end
      end

      context 'when a sort is provided' do

        let(:document) do
          authorized_collection.find_one_and_replace(selector, { field: 'testing' }, :sort => { field: 1 })
        end

        it 'returns the original document' do
          expect(document['field']).to eq('test1')
        end
      end
    end

    context 'when no matching document is found' do

      context 'when no upsert options are provided' do

        let(:selector) do
          { field: 'test5' }
        end

        let(:document) do
          authorized_collection.find_one_and_replace(selector, { field: 'testing' })
        end

        it 'returns nil' do
          expect(document).to be_nil
        end
      end

      context 'when upsert options are provided' do

        let(:selector) do
          { field: 'test5' }
        end

        let(:document) do
          authorized_collection.find_one_and_replace(selector, { field: 'testing' }, :upsert => true, :return_document => :after)
        end

        it 'returns the new document' do
          expect(document['field']).to eq('testing')
        end
      end
    end

    context 'when max_time_ms is provided' do

      it 'includes the max_time_ms value in the command' do
        expect {
          authorized_collection.find_one_and_replace(selector, { field: 'testing' }, max_time_ms: 0.1)
        }.to raise_error(Mongo::Error::OperationFailure)
      end
    end

    context 'when the operation fails' do

      let(:result) do
        authorized_collection.find_one_and_replace(selector, { field: 'testing' }, max_time_ms: 0.1)
      end

      it 'raises an OperationFailure' do
        expect {
          result
        }.to raise_exception(Mongo::Error::OperationFailure)
      end
    end

    context 'when collection has a validator' do
      min_server_version '3.2'

      around(:each) do |spec|
        authorized_client[:validating].drop
        authorized_client[:validating,
                          :validator => { :a => { '$exists' => true } }].tap do |c|
          c.create
        end
        spec.run
        collection_with_validator.drop
      end

      before do
        collection_with_validator.insert_one({ a: 1 })
      end

      context 'when the document is valid' do

        let(:result) do
          collection_with_validator.find_one_and_replace(
            { a: 1 }, { a: 5 }, :return_document => :after)
        end

        it 'replaces successfully when document is valid' do
          expect(result[:a]).to eq(5)
        end
      end

      context 'when the document is invalid' do

        context 'when bypass_document_validation is not set' do

          let(:result2) do
            collection_with_validator.find_one_and_replace(
              { a: 1 }, { x: 5 }, :return_document => :after)
          end

          it 'raises OperationFailure' do
            expect {
              result2
            }.to raise_exception(Mongo::Error::OperationFailure)
          end
        end

        context 'when bypass_document_validation is true' do

          let(:result3) do
            collection_with_validator.find_one_and_replace(
              { a: 1 }, { x: 1 }, :bypass_document_validation => true,
              :return_document => :after)
          end

          it 'replaces successfully' do
            expect(result3[:x]).to eq(1)
            expect(result3[:a]).to be_nil
          end
        end
      end
    end

    context 'when write_concern is provided', if: standalone? do
      min_server_version '3.2'

      it 'uses the write concern' do
        expect {
          authorized_collection.find_one_and_replace(selector,
                                                     { field: 'testing' },
                                                     write_concern: { w: 2 })
        }.to raise_error(Mongo::Error::OperationFailure)
      end
    end

    context 'when the collection has a write concern', if: standalone? do
      min_server_version '3.2'

      let(:collection) do
        authorized_collection.with(write: { w: 2 })
      end

      it 'uses the write concern' do
        expect {
          collection.find_one_and_replace(selector,
                                          { field: 'testing' },
                                          write_concern: { w: 2 })
        }.to raise_error(Mongo::Error::OperationFailure)
      end
    end

    context 'when collation is provided' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.find_one_and_replace(selector,
                                                   { name: 'doink' },
                                                   options)
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      let(:options) do
        { collation: { locale: 'en_US', strength: 2 } }
      end

      context 'when the server selected supports collations', if: collation_enabled? do

        it 'applies the collation' do
          expect(result['name']).to eq('bang')
          expect(authorized_collection.find(name: 'doink').count).to eq(1)
        end
      end

      context 'when the server selected does not support collations', unless: collation_enabled? do

        it 'raises an exception' do
          expect {
            result
          }.to raise_exception(Mongo::Error::UnsupportedCollation)
        end

        context 'when a String key is used' do

          let(:options) do
            { 'collation' => { locale: 'en_US', strength: 2 } }
          end

          it 'raises an exception' do
            expect {
              result
            }.to raise_exception(Mongo::Error::UnsupportedCollation)
          end
        end
      end
    end

    context 'when collation is not specified' do

      let(:selector) do
        { name: 'BANG' }
      end

      let(:result) do
        authorized_collection.find_one_and_replace(selector, { name: 'doink' })
      end

      before do
        authorized_collection.insert_one(name: 'bang')
      end

      it 'does not apply the collation' do
        expect(result).to be_nil
      end
    end
  end

  describe '#watch' do

    context 'when change streams can be tested', if: test_change_streams? do

      let(:change_stream) do
        authorized_collection.watch
      end

      let(:enum) do
        change_stream.to_enum
      end

      before do
        change_stream
        authorized_collection.insert_one(a: 1)
      end

      context 'when no options are provided' do

        context 'when the operation type is an insert' do

          it 'returns the change' do
            expect(enum.next[:fullDocument][:a]).to eq(1)
          end
        end

        context 'when the operation type is an update' do

          before do
            authorized_collection.update_one({ a: 1 }, { '$set' => { a: 2 } })
          end

          let(:change_doc) do
            enum.next
            enum.next
          end

          it 'returns the change' do
            expect(change_doc[:operationType]).to eq('update')
            expect(change_doc[:updateDescription][:updatedFields]).to eq('a' => 2)
          end
        end
      end

      context 'when options are provided' do

        context 'when full_document is updateLookup' do

          let(:change_stream) do
            authorized_collection.watch([], full_document: 'updateLookup').to_enum
          end

          before do
            authorized_collection.update_one({ a: 1 }, { '$set' => { a: 2 } })
          end

          let(:change_doc) do
            enum.next
            enum.next
          end

          it 'returns the change' do
            expect(change_doc[:operationType]).to eq('update')
            expect(change_doc[:fullDocument][:a]).to eq(2)
          end
        end

        context 'when batch_size is provided' do

          before do
            Thread.new do
              sleep 1
              authorized_collection.insert_one(a: 2)
              authorized_collection.insert_one(a: 3)
            end
          end

          let(:change_stream) do
            authorized_collection.watch([], batch_size: 2)
          end

          it 'returns the documents in the batch size specified' do
            expect(change_stream.instance_variable_get(:@cursor)).to receive(:get_more).once.and_call_original
            enum.next
          end
        end

        context 'when collation is provided' do

          before do
            authorized_collection.update_one({ a: 1 }, { '$set' => { a: 2 } })
          end

          let(:change_doc) do
            enum.next
          end

          let(:change_stream) do
            authorized_collection.watch([ { '$match' => { operationType: 'UPDATE'}}],
                                        collation: { locale: 'en_US', strength: 2 } ).to_enum
          end

          it 'returns the change' do
            expect(change_doc['operationType']).to eq('update')
            expect(change_doc['updateDescription']['updatedFields']['a']).to eq(2)
          end
        end
      end
    end
  end
end